Unit 4, Chapter 10: The Digestive System Flashcards

1
Q

Define Alimentary Canal

A

The tube through which food is processed, beginning at the mouth and ending at the anus; also known as the digestive tract.

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2
Q

Define Amino Acid

A

A building block of protein.

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3
Q

Define Bile

A

A greenish-yellow fluid secreted by the liver that helps digest fat.

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4
Q

Define Chemical Digestion

A

The chemical breakdown of nutrient molecules into smaller molecules by enzyme action.

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5
Q

Define Chyme

A

A thick liquid produced in the stomach and made of digested food combined with gastric juice.

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6
Q

Define Cirrhosis

A

The irreversible replacement of healthy liver tissue with non-functioning scar tissue; most commonly caused by excessive alcohol intake or hepatitis.

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7
Q

Define Crohn’s Disease

A

A form of inflammatory disease that can affect any part of the alimentary canal from the mouth to the anus.

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8
Q

Define Diabetes

A

A condition in which the body is unable to use glucose for energy.

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9
Q

Define Disaccharide

A

A sugar made up of two monosaccharide molecules.

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10
Q

Define Duodenum

A

A short, wide U-shaped section of the small intestine into which food passes from the stomach.

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11
Q

Define Enzyme

A

A protein molecule that helps speed up important chemical reactions in the body.

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12
Q

Define Esophagus

A

The muscular tube through which food passes from the mouth to the stomach.

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13
Q

Define Essential Nutrient

A

A nutrient that cannot be made by the body, and must therefore be obtained from food.

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14
Q

Define Gastric Juice

A

A mixture of hydrochloric acid, salts, enzymes, water, and mucus that is produced by glands in the stomach to help digest food.

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15
Q

Define Glycogen

A

A polysaccharide made up of glucose units.

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16
Q

Define Hepatitis

A

Inflammation of the liver, most commonly caused by a virus.

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17
Q

Define Hydrolysis

A

A chemical reaction in which water breaks apart macromolecules into smaller molecules.

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18
Q

Define Ileum

A

The portion of the small intestine that follows immediately after the jejunum.

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19
Q

Define Inflammatory Bowel Disease

A

The general name for a group of diseases that cause inflammation in the intestines.

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20
Q

Define Jujunum

A

The portion of the small intestine that follows immediately after the duodenum.

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21
Q

Define Lipid

A

An organic compound that does not dissolve in water, such as fat and oil.

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22
Q

Define Macromolecule

A

A very large molecule made up of smaller molecules that are linked together.

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23
Q

Define Mechanical Digestion

A

The physical breakdown of large pieces of food into smaller pieces in the mouth by the action of teeth, beak, or other similar structures, and by contractions and chrning motions in the stomach.

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24
Q

Define Metabolism

A

The sum total of all of the chemical reactions that occur in an organism.

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25
Q

Define Monosaccharide

A

A simple sugar with three to seven carbon atoms.

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26
Q

Define Pepsin

A

An enzyme in gastric juice that helps break down proteins into polypeptides.

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27
Q

Define Peptic Ulcer

A

A sore in the lining of the stomach or duodenum most commonly caused by infection with the bacterium Helicobacter pylori.

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28
Q

Define Peptide Bond

A

A bond that holds together the amino acids in a protein.

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29
Q

Define Peristalsis

A

A wave-like series of muscular contractions in the esophagus.

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30
Q

Define Polypeptide

A

A linear chain of several amino acids linked by peptide bonds.

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31
Q

Define Polysaccharide

A

A large molecule made up of many linked monosaccharide molecules.

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32
Q

Define Saliva

A

A watery secretion in the mouth that begins the digestive process.

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33
Q

Define Salivary Glands

A

Glands in the mouth that produce saliva to begin the chemical digestion of food.

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34
Q

Define Ulcerative Colitis

A

A form of inflammatory disease that attacks the colon.

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35
Q

Define Villi

A

Finger-like projections lining the surface of the small intestine that increase the surface area to improve the absorption of nutrients.

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36
Q

What does the letter A represent on the diagram below?

A

Teeth

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37
Q

What does the letter B represent on the diagram below?

A

Tongue

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38
Q

What does the letter C represent on the diagram below?

A

Esophagus

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39
Q

What does the letter D represent on the diagram below?

A

Liver

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40
Q

What does the letter E represent on the diagram below?

A

Gall Bladder

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41
Q

What does the letter F represent on the diagram below?

A

Small Intestine

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42
Q

What does the letter G represent on the diagram below?

A

Appendix

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43
Q

What does the letter H represent on the diagram below?

A

Salivary Glands

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44
Q

What does the letter I represent on the diagram below?

A

Stomach

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45
Q

What does the letter J represent on the diagram below?

A

Pancreas

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46
Q

What does the letter K represent on the diagram below?

A

Large Intestine

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47
Q

What does the letter L represent on the diagram below?

A

Anus

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48
Q

Which letter represents the stomach on the diagram below?

A

I

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49
Q

Which letter represents the teeth on the diagram below?

A

A

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50
Q

Which letter represents the tongue on the diagram below?

A

B

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51
Q

Which letter represents the esophagus on the diagram below?

A

C

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52
Q

Which letter represents the liver on the diagram below?

A

D

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53
Q

Which letter represents the gall bladder on the diagram below?

A

E

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54
Q

Which letter represents the small intestine on the diagram below?

A

F

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55
Q

Which letter represents the appendix on the diagram below?

A

G

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56
Q

Which letter represents the salivary glands on the diagram below?

A

H

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57
Q

Which letter represents the pancreas on the diagram below?

A

J

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58
Q

Which letter represents the large intestine on the diagram below?

A

K

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59
Q

Which letter represents the anus on the diagram below?

A

L

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60
Q

What is the tube through which food is processed, beginning at the mouth and ending at the anus, known as?

A

Alimentary Canal

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61
Q

What is a building block of protein known as?

A

Amino Acid

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62
Q

What is a greenish-yellow fluid secreted by the liver that helps digest fat known as?

A

Bile

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63
Q

What is the chemical breakdown of nutrient molecules into smaller molecules by enzyme action known as?

A

Chemical Digestion

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64
Q

What is a thick liquid produced in the stomach and made of digested food combined with gastric juice known as?

A

Chyme

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65
Q

What is the irreversible replacement of healthy liver tissue with non-functioning scar tissue which is most commonly caused by excessive alcohol intake or hepatitis known as?

A

Cirrhosis

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66
Q

What is a form of inflammatory disease that can affect any part of the alimentary canal from the mouth to the anus known as?

A

Crohn’s Disease

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67
Q

What is a condition in which the body is unable to use glucose for energy known as?

A

Diabetes

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68
Q

What is a sugar made up of two monosaccharide molecules known as?

A

Disaccharide

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69
Q

What is a short, wide U-shaped section of the small intestine into which food passes from the stomach known as?

A

Duodenum

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70
Q

What is a protein molecule that helps speed up important chemical reactions in the body known as?

A

Enzyme

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71
Q

What is the muscular tube through which food passes from the mouth to the stomach known as?

A

Esophagus

72
Q

What is a nutrient that cannot be made by the body, and must therefore be obtained from food known as?

A

Essential Nutrient

73
Q

What is a mixture of hydrochloric acid, salts, enzymes, water, and mucus that is produced by glands in the stomach to help digest food known as?

A

Gastric Juice

74
Q

What is a polysaccharide made up of glucose units known as?

A

Glycogen

75
Q

What is inflammation of the liver, most commonly caused by a virus known as?

A

Hepatitis

76
Q

What is a chemical reaction in which water breaks apart macromolecules into smaller molecules known as?

A

Hydrolysis

77
Q

What is the portion of the small intestine that follows immediately after the jejunum known as?

A

Ileum

78
Q

What is the general name for a group of diseases that cause inflammation in the intestines known as?

A

Inflammatory Bowel Disease

79
Q

What is the portion of the small intestine that follows immediately after the duodenum known as?

A

Jejunum

80
Q

What is an organic compound that does not dissolve in water, such as fat and oil, known as?

A

Lipid

81
Q

What is a very large molecule made up of smaller molecules that are linked together known as?

A

Macromolecule

82
Q

What is the physical breakdown of large pieces of food into smaller pieces in the mouth by the action of teeth, beak, or other similar structures, and by contractions and chrning motions in the stomach known as?

A

Mechanical Digestion

83
Q

What is the sum total of all of the chemical reactions that occur in an organism known as?

A

Metabolism

84
Q

What is a simple sugar with three to seven carbon atoms known as?

A

Monosaccharide

85
Q

What is an enzyme in gastric juice that helps break down proteins into polypeptides known as?

A

Pepsin

86
Q

What is a sore in the lining of the stomach or duodenum most commonly caused by infection with the bacterium Helicobacter pylori known as?

A

Peptic Ulcer

87
Q

What is a bond that holds together the amino acids in a protein known as?

A

Peptide Bond

88
Q

What is a wave-like series of muscular contractions in the esophagus known as?

A

Peristalsis

89
Q

What is a linear chain of several amino acids linked by peptide bonds known as?

A

Polypeptide

90
Q

What is a large molecule made up of many linked monosaccharide molecules known as?

A

Polysaccharide

91
Q

What is a watery secretion in the mouth that begins the digestive process known as?

A

Saliva

92
Q

What are glands in the mouth that produce saliva to begin the chemical digestion of food known as?

A

Salivary Glands

93
Q

What is a form of inflammatory disease that attacks the colon known as?

A

Ulcerative Colitis

94
Q

What are finger-like projections lining the surface of the small intestine that increase the surface area to improve the absorption of nutrients known as?

A

Villi

95
Q

What is the primary function of carbohydrates in the human body?

A

Carbohydrates serve as short-term or long-term energy storage in the body.

96
Q

What is the difference bertween a monosaccharide and a disaccharide? Give an example of each.

A

A monosaccharide is a single-ringed or single-unit sugar, such as glucose or fructose. A disaccharide is formed by a bond between two monosaccharides; examples of disaccharides are sucrose, maltose, and lactose.

97
Q

Explain how macromolecules are borken down for use in the body.

A

Macromolecules are chemically broken down by enzymatic hydrolysis, which uses water and enzymes to disassemble large biological molecules into smaller molecules for absorption by body cells.

98
Q

If an athlete runs for 15 minutes, which macromolecules are likely to break down first in the athlete’s body?

A

Carbohydrates are likely to be used first as a quick, short-term energy source.

99
Q

Which macromolecules would provide the greatest benefit as a long-term energy storage molecule to a bird that migrates long distances?

A

Although carbohydrates can function in long-term energy storage, lipids would provide the greatest benefit because they store more energy per gram compared to carbohydrates.

100
Q

Describe where the digestion of carbohydrates begins in the body, the major glands involved, and the digestive secretions produced.

A

Digestion of carbohydrates begins as soon as food enters the mouth when the salivary glands release saliva, which contains enzymes (e.g., amylase) that start the chemical digestion process.

101
Q

Explain how peristalsis works in the esophagus and its function in digestion.

A

Peristalsis is a form of mechanical digestion that involves a series of wave-like muscular contractions of longitudinal and circular muscles. The contractions move the bolus down the esophagus to the stomach for further digestion.

102
Q

Analyze whether the epiglottis is closed and covering the trachea or open in the following situation, and explain why:

When the person is talking.

A

Open, for air exchange and access to the trachea.

103
Q

Analyze whether the epiglottis is closed and covering the trachea or open in the following situation, and explain why:

When the person is swallowing.

A

Closed, to prevent food entering the trachea.

104
Q

Analyze whether the epiglottis is closed and covering the trachea or open in the following situation, and explain why:

When the person is coughing.

A

Open, because coughing involves exhaling, which requires the trachea to be open.

105
Q

Analyze whether the epiglottis is closed and covering the trachea or open in the following situation, and explain why:

When the person is chewing.

A

Open, until swallowing occurs.

106
Q

If a person has the mumps, their submandibular glands are swollen. Decide which part of the body a doctor would examins to help diagnose the mumps.

A

A doctor would examine the neck area under the jaw line on each side of the body to feel for swelling of the submandibular glands.

107
Q

Using your knowledge of basic chemistry from previous studies, how do over-the-counter antacids, such as calcium carbonate, help an individual with a gastroesophageal discomfort, such as stomach pain.

A

Gastroesophageal pain may be due to high acid levels. Over-the-counter antacids are medicines that work by increasing the pH in the digestive tract due to a base, like calcium carbonate, acting to neutralize the pH level.

108
Q

Explain two functions of pancreatic fluid.

A

Pancreatic fluid delivers enzymes for the breakdown of foods. It also produces bicarbonate to neutralize acidity, which increases enzymatic efficiency.

109
Q

What happens to fats before they are digested and absorbed by the intestinal cells? Explain why this occurs.

A

Before fats are digested, insoluble fat droplets are emulsified into smaller fat droplets by bile salts. This allows for a greater surface area to be exposed for digestive enzymes to break lipids down in the small intestine.

110
Q

What happens to partially digested food after it leaves the stomach, up to the stage where it leaves the small intestine?

A

Chyme frst passes through the f rst part of the small intestine, the duodenum, where it receives digestive secretions from the pancreas, liver, and the gall bladder. Next, the chyme and digestive juice mixture moves into the lower part of the small intestine (jejunum and ileum), where more digestion occurs and nutrients are absorbed into the bloodstream.

111
Q

What is the role of the gall bladder in digestion?

A

The gall bladder stores the bile produced by the liver. Bile contains bile salts that digest the insoluble fats by breaking up the fat droplets so they are easier to digest and absorb.

112
Q

A family member has recently had a cholecystectomy, a surgical procedure to remove his gall bladder. Now he must take medication to prevent diarrhea. Why would the removal of the gall bladder cause diarrhea?

A

The gall bladder stores the acidic bile between meals. Without the gall bladder to store the bile being produced, the highly acidic bile would be steadily released into the intestines, even when there is no food present to dilute it, thus causing chronic diarrhea.

113
Q

A baby is born with a mutations that results in an unusually smooth small intestine that has far fewer villi than a normal small intestine. Describe the possible consequences of this mutation.

A

A smooth small intestine would result in food passing through more quickly, and fewer villi would result in lower nutrient absorption. This could result in malnutrition.

114
Q

How do Helicobacter pylori cause peptic ulcers? Explain your answer.

A

Helicobacter pylori are bacteria that prevent mucus production in the walls of digestive tract. Without mucus, the acids in the stomach come into contact with and destroy the lining of the stomach, causing the formation of an ulcer.

115
Q

Identify some lifestyle changes that can reduce the risk of developing a gallstone.

A

Losing weight, eating properly, and cutting down alcohol intake can all reduce the risk of developing a gallstone.

116
Q

Why might Crohn’s disease be difficult to diagnose?

A

Diagnosis may be difficult because the symptoms of Crohn’s disease are similar to other intestinal bowel disorders, such as ulcerative colitis, and because Crohn’s disease can occur in any part of the very long alimentary canal.

117
Q

Distinguish between inflammatory bowel disease, Crohn’s disease, and ulcerative colitis, and describe in which part of the digestive tract each disease occurs.

A

Inflammatory bowel disease is a group of diseases that cause inflammation in the intestines. These diseases include Crohn’s disease and ulcerative colitis. Crohn’s disease is a form of IBD that can affect any part of the alimentary canal from the mouth to the anus. Ulcerative colitis is a form of IBD that specifically attacks the colon.

118
Q

Define the following disorder of the digestive system, and identify the causes of it.

Constipation

A

Constipation is a condition in which bowel movements are infrequent and strained; it can be caused by inadequate water intake, inadequate fibre in the diet, and lack of good muscle and nerve function in the bowel.

119
Q

Define the following disorder of the digestive system, and identify the causes of it.

Hepatitis

A

Hepatitis is an inflammation of the liver caused by contaminated drinking water (hepatitis A), infection through sexual contact (hepatitis B), or by contact with infected blood (hepatitis C).

120
Q

Define the following disorder of the digestive system, and identify the causes of it.

Cirrhosis

A

Cirrhosis is a chronic disease in which scar tissue replaces healthy liver tissue and the liver ceases to function properly. The most common causes of cirrhosis are chronic alcoholism and hepatitis C.

121
Q

Why are coffee and citrus fruits, such as oranges and grapefruits, not recommended for patients with ulcers?

A

Both coffee and citrus fruits are acidic, which would aggravate the ulcers.

122
Q

There are four major categories of macromolecules that contain the essential nutrients needed to maintain life: _____, _____, _____, and _____.

A

There are four major categories of macromolecules that contain the essential nutrients needed to maintain life: carbohydrates, lipids, proteins, and nucleic acids.

123
Q

Macromolecules are chemically broken down by _____, a process that uses certain enzymes as _____.

A

Macromolecules are chemically broken down by hydrolysis, a process that uses certain enzymes as catalysts.

124
Q

_____ helps transport materials around the body, lubricate joints, form vital fluids such as blood, and regulate body temperature.

A

Water helps transport materials around the body, lubricate joints, form vital fluids such as blood, and regulate body temperature.

125
Q

To digest their food, most animals have a digestive tract that consists of a tube known as the _____.

A

To digest their food, most animals have a digestive tract that consists of a tube known as the alimentary canal.

126
Q

The four stages of food processing in animals are _____, _____ (mechanical and chemical), _____, and _____.

A

The four stages of food processing in animals are ingestion, digestion (mechanical and chemical), absorption, and elimination.

127
Q

The human digestive system is made up of the _____ and three accessory organs: the _____, the _____ and the _____.

A

The human digestive system is made up of the alimentary canal and three accessory organs: the liver, the pancreas and the gall bladder.

128
Q

Food is transported from the esophagus to the stomach by wave-like muscular contractions known as _____.

A

Food is transported from the esophagus to the stomach by wave-like muscular contractions known as peristalsis.

129
Q

Although chemical digestion begins in the mouth and continues in the stomach, most chemical digestion occurs in the _____.

A

Although chemical digestion begins in the mouth and continues in the stomach, most chemical digestion occurs in the small intestine.

130
Q

The _____ absorbs water from the alimentary canal and forms _____, which are eliminated as solid waste.

A

The large intestine absorbs water from the alimentary canal and forms feces, which are eliminated as solid waste.

131
Q

Different types of enzymes are involved in the chemical digestion of _____, _____ and _____.

A

Different types of enzymes are involved in the chemical digestion of carbohydrates, proteins and fats.

132
Q

The levels of _____ differ through the digestive system, to allow optimum enzyme function.

A

The levels of pH differ through the digestive system, to allow optimum enzyme function.

133
Q

_____ in the alimentary canal are primarily caused by the bacteria Helicobacter pylori.

A

Ulcers in the alimentary canal are primarily caused by the bacteria Helicobacter pylori​.

134
Q

_____ is a group of chronic diseases that cause inflammation in the intestines.

A

Inflammatory bowel disease is a group of chronic diseases that cause inflammation in the intestines.

135
Q

Technological advances such as _____ and _____ enable doctors to diagnose and treat many diseases of the alimenatry canal without the need for invasive surgery.

A

Technological advances such as medical imaging technology and endoscopy enable doctors to diagnose and treat many diseases of the alimenatry canal without the need for invasive surgery.

136
Q

The _____ secretes insulin that regulates the absorption of the _____ from the small intestine; diabetes results when there is insufficient insulin to regulate _____.

A

The pancreas secretes insulin that regulates the absorption of the glucose from the small intestine; diabetes results when there is insufficient insulin to regulate blood glucose levels.

137
Q

Genetically engineered human _____ and computerized _____ pumps are some of the technological innovations used in the control and maintenance of blood glucose levels.

A

Genetically engineered human insulin and computerized insulin pumps are some of the technological innovations used in the control and maintenance of blood glucose levels.

138
Q

What are the four major macromolecules that are needed by the body, and why are they important?

A

The four macromolecules are carbohydrates, lipids, proteins, and nucleic acids. They are used to maintain the body’s metabolism, provide the energy that the body’s cells need to carry out cellular activities, and to build and repair body tissues.

139
Q

Summarize the functions of lipids in the body.

A

Lipids build cell membranes, help protect vital organs from injury, insulate the body from cold, and function as energy storage molecules.

140
Q

Compare and contrast monosaccharides, disaccharides, and polysaccharides.

A

All carbohydrates have the molecular formula CH2O, and that most carbohydrates function in energy storage. T e molecules of monosaccharides (single sugar), disaccharides (two sugars), and polysaccharides (many sugars) differ in size and in their number of sugar units. There are different types of each of these sugars in plants and animals.

141
Q

For carbohydrates, make a list of the characteristics that define the grouping including structure, function, exampls and the digestive enxymes that make them usable by the body.

A

Structure: two hydrogens and one oxygen for every carbon

Function: provide materials for building cell membranes, source of quick energy

Example: glucose

Digestive Enzyme: carbohydrases

142
Q

For proteins, make a list of the characteristics that define the grouping including structure, function, exampls and the digestive enxymes that make them usable by the body.

A

Structure: hundreds of amino acids linked by peptide bonds

Function: structure and support for blood cells, tissues, and muscles, aid in contraction, catalysts for chemical reactions, immunity against infections and disease, transport ions

Example: insulin

Digestive Enzyme: proteases

143
Q

For lipids, make a list of the characteristics that define the grouping including structure, function, exampls and the digestive enxymes that make them usable by the body.

A

Structure: glycerol molecule (three carbons and a fatty acid chain)

Function: store energy reserves, cushioning and insulation for internal organs, materials to build cell membranes

Example: oils

Digestive Enzyme: lipases

144
Q

For nucleic acids, make a list of the characteristics that define the grouping including structure, function, exampls and the digestive enxymes that make them usable by the body.

A

Structure: double helix

Function: contain genetic information

Example: DNA

Digestive Enzyme: nucleases

145
Q

Why is a polysaccharide considered a long-term source of energy, while a monosaccharide is considered a short-term source of energy?

A

It takes longer to break down a polysaccharide into simple sugars, which the body is able to use quickly to release energy.

146
Q

A dessert topping for ice cream contains maltose, soybean oil, and salt. Identify the kinds of macromolecules and minerals that are in this topping.

A

Maltose is a simple sugar carbohydrate, soybean oil is a lipid, and salt contains the mineral sodium.

147
Q

Why must macromolecules be broken down into smaller molecules during digestion?

A

Most macromolecules are too large to enter cells directly. Enzymatic hydrolysis disassembles large molecules into smaller molecules so that cells can absorb these smaller molecules for the body to use.

148
Q

In your own words, describe the structure of a protein.

A

Amino acids are joined together by peptide bonds to form a polypeptide, and one or more polypeptides make up a protein.

149
Q

Explain why humans cannot survive for more than a few days without drinking water.

A

Water is considered the most important molecule in the body because it makes up about two-thirds of the body’s mass and performs vital functions such as transporting nutrients, eliminating toxins, and regulating body temperature.

150
Q

Which vitamin is involved in the absorption of calcium from foods?

A

Vitamin D

151
Q

Identify a vitamin that would be useful to take for night blindness.

A

vitamin A

152
Q

What vitamin deficiency could lead to bone malformations?

A

Vitamins A and D

153
Q

To prevent cramping during a soccer match, an athlete is advised to eat a banana and drink a glass of milk before the game. Explain why these foods might be helpful in preventing cramps.

A

Milk is a good source of the mineral calcium which is important for proper muscle function. Bananas are a good source of potassium which also functions in muscle contraction and may prevent muscle cramping.

154
Q

Classify the following organism as a filter feeder, fluid feeder, substrate feeder, or bulk feeder.

An animal that feeds on plant sap has a long beak-like mouthpart that can pierce plant tissues,

A

Fluid Feeder

155
Q

Classify the following organism as a filter feeder, fluid feeder, substrate feeder, or bulk feeder.

An animal eats its way through the upper surface of a leaf.

A

Substrate Feeder

156
Q

Classify the following organism as a filter feeder, fluid feeder, substrate feeder, or bulk feeder.

An animal captures its prey with its teeth and tears off pieces of meat.

A

Bulk Feeder

157
Q

Classify the following organism as a filter feeder, fluid feeder, substrate feeder, or bulk feeder.

An aquatic animal has gills in which mucus traps food.

A

Filter Feeder

158
Q

A biologist studying the alimentary canal in animals notices that herbivores such as deer have an enlarged cecum, whereas carnivores like foxes have a small cecum or none at all. The researcher also finds that the cecum hosts a high concentration of bacteria. How might the concentration of bacteria be related to the size of the cecum in herbivores?

A

A large cecum not only has a larger surface area for better nutrient absorption of plant material, but it also has more room for hosting bacteria that help in the enzymatic breakdown of plant cellulose.

159
Q

Identify the body part(s) in where digestion of carbohydrates occurs.

A

A (mouth) and I (small intestine)

160
Q

Identify where digestion of proteins occurs.

A

G (stomach) and I (small intestine)

161
Q

Which is the longest section of the alimentary canal?

A

I (most digestion and nutrient absorption occurs here and a large surface area facilitates these processes)

162
Q

Where does most absorption in the digestive system take place?

A

D (large intestine)

163
Q

Compare the chemical digestion of the four types of macromolecules as they move through the following body parts: oral cavity, esophagus, small intestine, and large intestine. Include any enzymatic digestion that occurs along the way.

A
  • carbohydrates are digested in the mouth by the action of amylase and broken down further by pancreatic amylase in the small intestine
  • proteins are broken down by pepsin in the stomach and further hydrolyzed by pancreatic enzymes in the small intestine
  • nucleic acids are broken down by nucleases in the small intestine
  • fats are broken down by bile salts and pancreatic lipases in the small intestine
  • no chemical digestion occurs in either the esophagus (it is for transport and swallowing only) or in the large intestine (which functions to absorb water from undigested material)
164
Q

The small intestine is divided into three different regions. Describe the structure and function of each of these regions.

A

The three different regions of the small intestine, and their structures and functions, are:

  • duodenum—U-shaped region immediately aft er the stomach, where food is combined with secretions from the pancreas and gall bladder as it passes through the digestive tract
  • jejunum—structure immediately following the duodenum; about 2.5 m long, it contains more folds than the duodenum; breaks down the remaining proteins and carbohydrates for absorption into the bloodstream
  • ileum—structure immediately following the jejunum; about 3 m long, it contains fewer and smaller villi than either the duodenum or jejunum; absorbs nutrients, and pushes the remaining undigested material into the large intestine
165
Q

Your friend is convinced that digestion begins in the stomach. Is this true or false? Explain your answer,

A

False. All foods are mechanically broken down in the mouth by chewing. Moreover, carbohydrates are chemically digested in the mouth due to salivary amylase.

166
Q

Infer how the food reaches an astronaut’s stomach when he or she is floating in zero gravity.

A

Food moves through the esophagus due to rhythmic, wave-like muscle movements called peristalsis, that move food from the throat into the stomach. This involves involuntary smooth muscles that will contract and relax independent of gravity.

167
Q

Why does the acid in gastric juices not damage the wall of the stomach?

A

The wall of the stomach is protected by mucus that acts as a barrier to prevent the highly acidic gastric juices from damaging the stomach wall.

168
Q

Which structural features of the small intestine increases surface area? Why is this important?

A

The walls of the small intestine are lined by folds which have finger-like projections called villi. The villi are surrounded by brush-like microvilli. The villi and microvilli greatly increase the surface area of the intestine so that nutrients can be more effectively absorbed.

169
Q

Why are most digestive enzymes not found in the stomach?

A

Proteins are digested in the stomach. Hence, digestive enzymes, which are proteins, would be broken down by the acidity in the stomach.

170
Q

In what ways would a digestive system that did not use mechanical digestion differ from one that does?

A

There would be an even greater requirement for chemical digestion to occur, and more potent enzymes might be required without mechanical forces to break up food.

171
Q

After playing in the dirt, a child sticks her fingers in her mouth and ingests a significant number of bacteria but does not get sick. Explain how this child’s digestive system protected her from these potentially toxic bacteria.

A

It is likely that the microbes were destroyed by the acidic conditions in the child’s stomach.

172
Q

What would an individual need to do to replace the function of their pancreas if their pancreas was removed?

A

The individual would require medications to replace the pancreatic enzymes necessary for digestion of carbohydrates, lipids, and proteins; they would also need regular insulin injections to replace the function of the pancreas.

173
Q

A new species of animal is found to have a digestive system that uses very little mechanical digestion. Describe its digestive tract.

A

There would be an even greater requirement for chemical digestion to occur and more potent enzymes might be required without mechanical forces to break up food. The small intestine might also have to be longer to allow more effective chemical digestion of food. The animal would also have few, if any, teeth for mechanical digestion.

174
Q

A nutritionist recommends drinking water before or after a meal, but not during a meal. Why might this be good advice?

A

It is possible that fluids could dilute digestive enzymes and change stomach acidity during feeding.

175
Q

Explain how your body absorbs water.

A

Water is absorbed from food matter passing through the large intestine.

176
Q

Summarize the structure and functions of the large intestine in humans.

A

The large intestine in humans is shorter and wider than the small intestine. The main function of the large intestine is to absorb water from the alimentary canal and to move feces into the rectum for storage and elimination.

177
Q
A